Antimicrobial susceptibility in Mannheimia haemolytica isolated from high-risk Stocker cattle after metaphylaxis and treatment
DOI:
https://doi.org/10.21423/aabppro20173340Keywords:
bovine respiratory disease, BRD, Metaphylaxis, antimicrobial resistance, Mannheimia haemolytica, M. haemolytica, Stocker cattleAbstract
Metaphylaxis (mass antimicrobial treatment) is commonly administered to high-risk cattle to limit bovine respiratory disease (BRD). While metaphylaxis decreases BRD morbidity and mortality, some cattle still require subsequent BRD treatments. Moreover, widespread application of anti-microbial drugs with extended duration of therapeutic concentrations in lung could increase antimicrobial resistance (AMR) in bacteria that cause BRD. Reports indicate increasing prevalence of AMR in Mannheimia haemolytica, the leading bacterial contributor to BRD in feedlot and Stocker cattle. The role that metaphylaxis has contributed to the recognized increase in AMR prevalence in M. haemolytica has not been well described. The impact of AMR on health outcomes in cattle managed to treat and control BRD is also not clear. The objective of this research was to describe the prevalence of AMR M. haemolytica in auction market-derived Stocker cattle that received a long acting macrolide for metaphylaxis, followed by treatment as necessary for BRD with other antimicrobials, over the first 21 days after receiving